This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Osteoarthritis affects more than half of the population above the age of 65 and has significant negative impact on the quality of life of elderly individuals. The economic costs in the US from OA have been estimated to be more than 1% of the gross domestic product. Recent research has led to the development of drugs that in experimental animals that have proven capable of protecting the macromolecules in cartilage from breakdown, effectively halting the progression of OA. Because of the long natural history of OA (10-20 years) validating the efficacy of these drugs in humans will require a technique that can directly assess their effect on the macromolecular matrix. Study Aims: 1. To obtain an estimate of the spatial difference of T1p throughout articular cartilage of the knee in asymptomatic subjects. 2. To obtain an estimate of the differences of T1p values in articular cartilage between different age groups of asymptomatic subjects. 3. To demonstrate that T1p-weighted MR imaging and calculated T1p maps can reliably detect foci of minimal osteoarthritis of articular cartilage as determined by arthoscopy.